According to a general steering system for changing a traveling direction of a vehicle, a steering column is connected to a steering wheel provided in front of a driver's seat, and the steering column for transmitting the operation of the steering wheel operates a rack gear mechanism to change the traveling direction of a vehicle.
In general, the steering system obtains information on a rotation angle or angular velocity of the steering wheel based on the linear motion of the traveling vehicle, and uses the information in an ECU to perform a roll control or a turning control. For this reason, a steering angle sensor for measuring the steering angle of the steering wheel is provided between the steering wheel and the steering column.
The steering angle sensor is rotated to correspond to the rotation of the steering wheel, and calculates an actual steering angle of the steering wheel. For example, the steering angle sensor is provided between the steering wheel and the steering column, and includes a housing that is connected to an electric connector so as to transmit signals to an ECU. A gear train, which is rotated by the rotation of the steering wheel and detects a rotation angle of the steering wheel, is provided in the housing. The steering angle sensor includes a PCB including a circuit that detects the rotation angle of the gear train, converts the rotation angle into electric signals, and transmits the signals to an ECU.
If the steering angle sensor accurately detects a steering angle and has a smaller size, it is possible to easily mount in a vehicle. For this reason, it is preferable that the entire size of the steering angle sensor be further reduced. However, according to a steering angle sensor that measures the rotation angle of the steering wheel by using a gear train, since dependent gears mesh with the outer periphery of a rotary member that rotate together with a steering wheel and are rotated, the steering angle sensor should have a size suitable for receiving the dependent gears meshing with the rotary member. For this reason, the steering angle sensor has a limitation in reducing the entire size thereof.